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Let $s(n):= sum_{dmid n,~d<n} d$ denote the sum of the proper divisors of $n$. It is natural to conjecture that for each integer $kge 2$, the equivalence [ text{$n$ is $k$th powerfree} Longleftrightarrow text{$s(n)$ is $k$th powerfree} ] holds almost always (meaning, on a set of asymptotic density $1$). We prove this for $kge 4$.
We consider the distribution in residue classes modulo primes $p$ of Eulers totient function $phi(n)$ and the sum-of-proper-divisors function $s(n):=sigma(n)-n$. We prove that the values $phi(n)$, for $nle x$, that are coprime to $p$ are asymptotical
A $k$-sum of a set $Asubseteq mathbb{Z}$ is an integer that may be expressed as a sum of $k$ distinct elements of $A$. How large can the ratio of the number of $(k+1)$-sums to the number of $k$-sums be? Writing $kwedge A$ for the set of $k$-sums of $
We define a new kind of classical digamma function, and establish its some fundamental identities. Then we apply the formulas obtained, and extend tools developed by Flajolet and Salvy to study more general Euler type sums. The main results of Flajol
We develop a new method for studying sums of Kloosterman sums related to the spectral exponential sum. As a corollary, we obtain a new proof of the estimate of Soundararajan and Young for the error term in the prime geodesic theorem.
We investigate various questions concerning the reciprocal sum of divisors, or prime divisors, of the Mersenne numbers $2^n-1$. Conditional on the Elliott-Halberstam Conjecture and the Generalized Riemann Hypothesis, we determine $max_{nle x} sum_{p